ESE's works engine tuner

[ken seeber]

Isn't that a bit like starting to smoke because you found a packet of cigarettes?

Frits, I guess the inverse of that is when a teenage guy starts chasing women cos he found he had a penis.

Wallace, if I had the choice of cylinder bore options (presuming you’re going to cast the cylinder and it looks like you have the gear), to me it would be:

1. Plate the bore. Heat transfer, durability and probably less total cost (time & $s) in the end.
2. Shrunk in liner. Ports can be accurately machined in with a dividing head. Any upsweep can be simply carefully filed in after the basic port is in place, ok at least for only a couple. However it does give you the ability to remove the liner and mod the ports a bit.
3. Cast in liner. Having seen the cast-in liner fall out after a cylinder (eg 70 – 90s Jap technology) is cut in half, I would never consider it. Interface was covered with gaps, coldshuts, black shit all around the exh port etc = crap heat transfer.

[husaberg]

3. Cast in liner. Having seen the cast-in liner fall out after a cylinder (eg 70 – 90s Jap technology) is cut in half, I would never consider it. Interface was covered with gaps, coldshuts, black shit all around the exh port etc = crap heat transfer.

Thats why Yamaha used to use corragated sleeves, that plus increased surface area, from memory the sleves are coated with something like zinc or some aluminum based oxide coating for better heat transfer prior to casting the cylinder arround it.
But yes coated one piece casting simpler and much better.

[Frits Overmars]

1. Plate the bore. Heat transfer, durability and probably less total cost (time & $s) in the end.
2. Shrunk in liner. Ports can be accurately machined in with a dividing head. Any upsweep can be simply carefully filed in after the basic port is in place, ok at least for only a couple. However it does give you the ability to remove the liner and mod the ports a bit.
3. Cast in liner.

Option #1 is best. But if for some reason it is out of the question, then take a look at option #4.
4: Pressed-in conical light-alloy plated liner. It was the method developed by Jan Thiel before he switched to option # 1.
Option #4 has all the advantages of option #2, plus the liner can be easily removed and refitted using a very slight press fit, without applying heat.
Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.

[marsheng]

Isn't that a bit like starting to smoke because you found a packet of cigarettes?

With a 2 stroke, I already smoke. Oh but what a nice smell.

[JanBros]

Option #1 is best. But if for some reason it is out of the question, then take a look at option #4.
4: Pressed-in conical light-alloy plated liner. It was the method developed by Jan Thiel before he switched to option # 1.
Option #4 has all the advantages of option #2, plus the liner can be easily removed and refitted using a very slight press fit, without applying heat.
Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.

For my honda Sky MX moped, I refuse to put money in expensive parts, so I only use originals.
I have cast iron big-bore cylinder that was on one of the engines I acquired and was thinking of making a sleeve for it to get it back to 50cc, and the advantage of the sleeve would be that I can use the sleeve to make a much wider double V-shaped exhaust port (compared to the original single port) gaining a lot of blowdown.
I suppose option 4 would be ok using a cast iron liner with a cast iron cylinder ?
any ideas on the minimum thickness of the sleeve for the exhaust-bridge to survive ?
does it has to be a specific type of cast iron (meaning can I turn one out of an ordinary piece of cast iron) ?

[marsheng]

This is probably going to be the most valuable bit of I of I gain from this thread.

From those in the know, and you are about to make a new cylinder, would you use the same as below or is there something you may want to change?

The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°

The next thing, if you have a non power valve exhaust, ie just a hole, would you change anything as above?

Lastly, would the port angles as above be different depending on bore ?

My guess is, it would all remain the same, but then I'm no expert.

What is the difference between RSW and RSA - If I search the forum I get - Nothing found. Probably to short for a search.

Thanks Wallace

[marsheng]

Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.

The problem with this could be that the insert and ports don't match. If I have my maths correct, 0.026 mm change in OD means the sleeve goes in 1 mm further.

I can see this being a great development tool. At the track, pop out the old liner and insert the new. You would need to make sure that cylinder head still seals correctly.

I have used straight sleeves many times and just heat is enough to drop the old sleeve out.

[F5 Dave]

If you are casting your own barrel there would have to be some super compelling reasons to not make a bridged or triple ex port. Esp without a PV.

But you want the ally tunnels well attached to the bore surface to strip heat away.
You'd still have to gain more than you'd achieve optomising ports on a single hole ex.

And presumably you will keep it period air cooled or Bears only so no concern?

I could send you a Rotax style pressure PV which could be a fairly easy mod to a water cooled arrangement.

[marsheng]

If you are casting your own barrel there would have to be some super compelling reasons to not make a bridged or triple ex port. Esp without a PV.

But you want the ally tunnels well attached to the bore surface to strip heat away.
You'd still have to gain more than you'd achieve optomising ports on a single hole ex.

And presumably you will keep it period air cooled or Bears only so no concern?

I could send you a Rotax style pressure PV which could be a fairly easy mod to a water cooled arrangement.

I do have a bridged port. What I meant by big holes is , no power valves or aux exhaust ports.

Needs to be period - Pre 82. I have a water cooled barrel here with a pressure type exhaust valve but that is 1983. Aghaaa.

[husaberg]

I do have a bridged port. What I meant by big holes is , no power valves or aux exhaust ports.

Needs to be period - Pre 82. I have a water cooled barrel here with a pressure type exhaust valve but that is 1983. Aghaaa.

The 125 Maico rs road race bikes were water cooled in the 70s as well as being disc valve induction
Pretty sure most mods are okay as long as they are undisguisable with regards to the outside appearance.

http://www.zweitakte.de/modelle/renn...RS250proto.htm

1979 Maico MD250 road bike

MAICO MD 250 WK-Cup machine


Its only cheating if you get caught
https://www.carthrottle.com/post/wqm9665/

[Grumph]

Needs to be period - Pre 82. I have a water cooled barrel here with a pressure type exhaust valve but that is 1983. Aghaaa.

If I can be looking at water cooling my "pre63" Villiers special on the basis of one pommy karter building a water cooled 9E in 1962, you've got no worries watercooling the Maico. You've simply found one of the rare 250 race bikes....

Precedent is everything.

[husaberg]

If I can be looking at water cooling my "pre63" Villiers special on the basis of one pommy karter building a water cooled 9E in 1962, you've got no worries watercooling the Maico. You've simply found one of the rare 250 race bikes....

Precedent is everything.

even looks like it has an Aprilia/Rotax RAVE power valve........
1934-1940 The XIVA (RY).water cooled with autolube or petroloil
http://www.users.globalnet.co.uk/~pa...cc/arc0596.htm

[Frits Overmars]

From those in the know, and you are about to make a new cylinder, would you use the same as below or is there something you may want to change?
The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°
if you have a non power valve exhaust, ie just a hole, would you change anything as above?

No.

would the port angles as above be different depending on bore?

Not depending on the bore, but on the stroke/bore-ratio.

What is the difference between RSW and RSA.

There is no difference in the porting of the late-model RSW and RSA cylinders.
But the RSA has better cooling (channels inside the inner curvatures of the transfer ducts) and two extra head studs that somehow contributed to power.

[Frits Overmars]

Jan used a morse cone angle (3° included angle if memory serves) on the cylinder bore inside and the sleeve's outside.
Of course you need not use a plated light-alloy liner; you can do the same thing with a cast-iron liner.

The problem with this could be that the insert and ports don't match. If I have my maths correct, 0.026 mm change in OD means the sleeve goes in 1 mm further.

Mathematically you're right. But that is without considering the press fit. It will not take much force to move the sleeve a little deeper.

[Frits Overmars]

The 125 Maico rs road race bikes were water cooled

I'd rather say they had a water cooled head cover. Coolant in the cylinder was hardly moving; cooling below the exhaust was non-existent.
Not the best solution if you want reliable power.